Click Settings (We are going to leave mosts defaults on for everything for this How-To)
Click Storage à With “IDE Storage” Selected click the Drive Icon with the plus sign on it à
Choose Add CD/DVD à Choose Disk à Navigate to the BT5 ISO you had downloaded
Click Display and assign at least 64MB
Click Ok
Open Terminal and enter the Following
VboxManage setextradata “Backtrack” “CustomVideoMode1″ “1100x740x16″

Click Start
Click inside the window –> Tab –> Choose “Backtrack Text”

Once the boot sequence completes you will already be in a root shell.

'NOTE: If you have chosen the KDE Environment do not forget to issue the following command before startx:

root@bt:~# rm /root/.kde/cache-*

Once Backtrack Launches Double Click the “Install Backtrack Icon” and follow the steps from here.